1. Field of the Invention
This invention relates to printed circuit boards generally and to the manufacturing of printed circuit boards.
2. Discussion of Related Art
A computer usually has an electronic assembly including a printed circuit board (PCB) and a processor die mounted to the PCB. Electrical components on different layers of the PCB are connected by generally cylindrical openings called vias that are formed through one or more layers of the PCB. The interior of each opening is lined with copper or another electrically conductive material. Metal lands formed on one or more layers of the PCB contact the via's electrically conductive lining and are connected to the PCB's electrical components by metal traces extending between the metal lands and the electrical components. Without the metal lands, it would be difficult, if not impossible, to form the necessary electrical connections.
The traditional approach outlined above is disadvantageous because forming vias consumes space within the PCB. For example, where vias are extended through multiple PCB layers, traces that are formed on the PCB layers and not connected to the vias must be routed around them. Consequently, areas of the PCB become crowded. Including metal lands on the PCB significantly increases the diameter of each via and further complicates the crowding problem. Additionally, forming the metal lands is time consuming and costly.